EFFECT OF DIFFERENT TEMPERATURE TREATMENTS ON PHYSIOLOGICAL TRANSFORMATION OF IN VITRO PHALAENOPSIS ‘FORTUNE SALTZMAN’ SEEDLINGS

Abstract

Phalaenopsis ‘Fortune Saltzman’ tissue culture seedlings were grown with 5 different day/night incubation temperatures (25/25ºC, 25/20ºC, 30/20ºC, 30/25ºC, and 35/25 º C). The seedlings used were clearly identified into three photosynthesis stages through CO2 rhythm detecting. In Stage I (21 days after planting, DAP) it showed a typical C3 plant carbon fixation pattern but when plants continued to grow to Stage II (45DAP) they exhibited similar type C3-CAM plants. After 120DAP, plants showed significantly decreased CO2 concentration at night, and showed a typical CAM plant carbon fixation pattern. The result showed that after 120 days, cultures with 30/20ºC and 30/25ºC incubation temperatures grew more stems and presented higher fresh weight and leaf lengths compared to the results of other treatments. Moreover, 30/25ºC treatment showed significantly higher responses in terms of dry weight, number of root, root length and number of leaf. The seedlings subjected to 30/25ºC treatment showed significantly higher levels of Rubisco enzyme activity than those subjected to the other treatments. Phosphoenolpyruvate carboxylase activities recorded during the night time in seedlings subjected to 30/25ºC incubation temperatures were also significant greater. Therefore, 30/25ºC treatment could advance growth of Phalaenopsis ‘Fortune Saltzman’ tissue culture seedlings faster and can be recommended for commercial production.